Personal computers and consumer electronic devices are used for a variety of entertainment functions. These entertainment functions can be roughly divided into two different types: that which uses computer-generated graphics, such as computer games; and that which uses compressed video streams, such as programs pre-recorded onto digital video disk (DVD), and digital programming provided to a set-top box by cable or satellite operators. The second type also includes encoding of analog video streams, such as performed by a digital video recorder (DVR).
Computer-generated graphics are typically generated by a graphics processing unit (GPU). A GPU is a specialized type of microprocessor found on computer game consoles and some personal computers. A GPU is optimized to perform fast rendering of three-dimensional primitive objects such as triangles, quadrilaterals, etc. The primitives are described with vertices, where each vertex has attributes (e.g., color), and textures can be applied to the primitives. The result of the rendering is a two-dimensional array of pixels which appears on a computer display or monitor.
Encoding and decoding of video streams involves computations of a different sort (e.g., discrete cosine transform, motion estimation, motion compensation, deblocking filters) These computations are typically handled by a general purpose central processing unit (CPU) in combination with specialized hardware logic such as application-specific integrated circuits (ASICs). Consumers therefore need multiple computing platforms to meet their entertainment needs. A single computing platform that handles both computer-generated graphics and video encoding and/or decoding is therefore desirable.